“I think he needs a big contract with boots because at this moment he doesn't have a deal with any brand – that's why he is playing with black boots," said the Portuguese.

“He finished his deal and now he is waiting for the right offer. I think he needs a brand to give him the right boots so he goes back to scoring goals.

“But jokes apart, he works amazingly well. I couldn't be happier with him.”

Mirror Football understands adidas, who are United’s official technical partners in a 10-year deal worth £750million, were keen to tie Lukaku down but have been unable to finalise terms.

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Mourinho, meanwhile, scolded Manchester United's great entertainers for almost choking when they should have been “smoking cigars.”

United were cruising at Vicarage Road on the back of Watford old boy Ashley Young's stunning pair of first-half goals and another from Anthony Martial in a 13-minute blitz.

But Troy Deeney's penalty and Abdoulaye Doucoure gave Mourinho the jitters until Jesse Lingard's superb, late solo stung the Hornets beyond repair.

Relieved United boss Mourinho admitted: “It was an easy match to win comfortably. We should have been smoking cigars but then we were in trouble.

“Out of nothing Watford got a penalty which gave them belief, and teams in mid-table can play with quality and no pressure. They had nothing to lose.

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“At 3-2 the game is in the balance, then Jesse had the initiative to kill the game.

“I prefer to forget about the five minutes where we lost concentration and focus on the many good things we did – so much in control, really dangerous in attacking situations to play away from home and score four goals where we could possibly have had seven or eight.

“I think they may have had a feeling it was too easy, that Watford had no conditions to react.

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“Maybe it is a good lesson – it is good to have a lesson without losing points. The next time we are winning 3-0, I hope the players will remember this.”

Young, gifted and back at the club where he cut his teeth and became a £9.75 million export to Aston Villa almost 11 years ago, opened the scoring with a crisp finish before whipping a magnificent 25-yard free-kick into the top corner six minutes later.

After an England recall earlier this month Young, 32, is on the brink of a new contract at Old Trafford and he said: “We had to dig deep, but once we got the goals it was a fantastic first half.

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“It started to get a bit nervy towards the end, but fortunately Jesse came up with the goods.

“It's always nice to get on the scoresheet, and I haven't done that (free-kick) for a long time, but tonight it was more important to get the three points.”